JPS619579A - Corrosion protecting method of steel structure - Google Patents

Abstract

PURPOSE:To remove completely old coated films and rust and simultaneously to carry out undercoating with phosphates, etc. by jetting high-pressure water added with a conversion coating treating agent such as phosphates when a steel structure is repainted. CONSTITUTION:The painting on the surface of an outdoor steel structure deteriorates with age, and the stripping off of coated films and rusting are caused. In this case, high-pressure water contg. 4-6% phosphates or 0.1-4.0% amine rust preventive or <=1.0% nitrite rust preventive is jetted. By said jetting, old paints and rust on the extremely minute rugged parts are completely striped off and removed, and the undercoating of the steel surface or the formation of phosphate films for improving corrosion resistance is simultaneously carried out. A corrosion protecting paint is successively coated only once, and the steel structure is easily coated again with a corrosion protecting paint.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is applicable to outdoor steel structures, etc. that exist in vast open spaces, such as belt conveyor equipment for transporting powder and granules installed in raw material yards of steel factories, etc. Regarding anti-corrosion construction methods.

(Prior art) In general, outdoor structures have weaknesses such as being exposed to wind and rain for many years after installation, or being built facing the sea due to factory location, and inevitably suffering from salt damage. Therefore, deterioration over time of the paint applied to the new steel structure cannot be avoided, and if left as it is, rusting and deterioration of the equipment are unavoidable.

Therefore, it is common practice to repaint steel structures from time to time in order to preserve them and extend their service life.However, in the conventional repainting method, it is necessary to use a ground preparation method and a shite hammer, wire brush, or moving crab. Since the treatment was carried out individually by workers using tools, it took a very long time, and the above method was not able to sufficiently remove rust from the surface to be painted of the structure, that is, the concave parts of the substrate, resulting in convexities on the substrate. There were variations in the state of remaining rust between the parts and the recesses, and even if such a substrate was coated with corrosion protection, rust defects could not be suppressed.

On the other hand, if you want to complete the so-called surface treatment, there are methods such as sandblasting and pickling, but since sand and powerful chemicals are used, high safety measures are required when handling them, and high costs are unavoidable. This is hardly a practical method.

(Purpose of the Invention) The present invention is used for repainting steel structures, and performs surface treatment evenly on the surface to be painted, and at the same time forms a chemical conversion film on the surface to be painted, thereby preventing rust. Along with deterrence,
Corrosion protection for steel structures that improves the adhesion of anticorrosive paint and allows a series of repainting treatments to be performed easily and extremely effectively by applying a single coat of anticorrosive paint containing anticorrosion pigments. Nichiru provides construction methods.

(Structure and operation of the invention) The present inventors have obtained the following knowledge as a result of various studies conducted prior to completing the present invention.

First of all, ① adopt a rust removal method that does not leave any rust-removal defects on the surface to be painted, that is, the substrate. ■Formation of a chemical conversion film after rust removal to completely prevent rust on the base surface. ■By improving the multiple coatings of conventional anti-corrosion paints and applying the anti-corrosion paint fi-1' with anti-rust pigments, it is possible to prolong the life of steel structures and simplify the painting process. The purpose of this method is to improve workability and save on paint, and its feature is that high-pressure water containing phosphate or the same effective agent is sprayed onto structural members to remove the previously painted film. At the same time, a chemical conversion film is formed on the surface to be painted, and then,
A method for preventing corrosion of steel structures by applying one coat of anti-corrosion paint containing anti-rust pigments.

Now, the present inventors have discovered that the previous paint film peeling of steel structures,
A jet spray of high-pressure water is used as a means to completely remove rust from the surface to be painted, that is, even the minute irregularities of the substrate, and a chemical conversion coating treatment agent such as phosphate is added to this high-pressure water. By doing so, it was possible to peel off the previously applied paint film and remove rust from the base surface, while at the same time forming a phosphoric acid film on the surface to be painted, that is, the base surface, achieving effective base treatment all at once. As a chemical conversion coating treatment agent added to high-pressure water,
As a phosphate, for example, Triona 505. ．． (Million Chemical Co., Ltd.), MP-7 (Daira Kogyo Co., Ltd.) and the like are preferably used as amine-based rust preventive agents, nitrite-based rust preventive agents, and the like.

In addition, conventionally used paints include base coat paint, intermediate coat paint, and top coat paint, etc., but the base coat paint uses rust-preventing pigments, and the vehicle is selected to have good adhesion to the substrate. Even if rust-preventing pigments are used as intermediate coatings, there is little or no scratching compared to the primer coating, and vehicles with good adhesion and a large film thickness have been used for both the primer and intermediate coatings. The reality is that there are. Furthermore, the topcoat paints do not use anti-rust pigments, but instead select vehicles and pigments that can withstand exposure environments, and add those that provide the necessary color development. Effective rust prevention can only be achieved by applying a top coat to the surface.

The HD paint used in the method of the present invention has all of these properties, and exhibits sufficient anti-corrosion and aesthetic effects when coated in multiple coats, and is used, for example, as a top coat. Oil-based phthalate resin paint (Tyco Marine)
Inu Nippon Paint Co., Ltd.), OR Paint (Nippon Paint Co., Ltd.), SD Marine Paint (Kansai Paint Co., Ltd.), etc., contain appropriate amounts of rust-preventing pigments such as zinc powder, synchromate, cyanamide lead, etc. Add and undercoat,
Desirable vehicles that simultaneously provide a top coating effect include salt rubber paints, epoxy resin paints, polyurethane resin paints, and silicone alkyd resin paints.

Furthermore, by using the chemical conversion coating treatment agent of the present invention, the effect of suppressing rust due to air intrusion (intrusion of oxygen source) etc. on the surface of the P1 coated body is expressed, and the adhesion with the top coat paint is extremely improved. You can get something good. in this way,
To obtain the mutual effect of rust suppression and topcoat, for example, in the case of phosphates, add 4 to 16% in high pressure water, and in the case of amine rust preventives, add 0.1 to 4.0%. In the case of a nitrite-based rust preventive agent, the diameter is preferably 1.0φ or less. This is because if the content of the chemical conversion coating treatment agent is too high, the rust suppression effect will decrease due to fluctuations in the high-pressure cleaning water and the interaction between the top coat and the treatment agent, and the addition of a high concentration of the treatment agent will increase the processing cost. leading to an increase in On the other hand, if the content of the treatment agent is low, the effect of forming a rust preventive film on the surface of the painted body is lost and the rust preventive effect is significantly reduced.

If necessary, especially if there is strong rust, dirt, or deposits that are difficult to remove, they can be easily removed by adding abrasives such as silica sand, iron powder, or coke powder to the high-pressure water. I can do it.

(Example and Effects) Next, in order to confirm the effects of the anti-corrosion construction method according to the present invention, a steel plate of an appropriate size was derusted using high-pressure washing water to which a chemical conversion coating treatment agent was added, and then a conventional top coat was applied. The method of the present invention involves applying one coat of paint with anti-corrosion pigment and vehicle added, and the method of the present invention, which involves applying a single coat of paint with anti-rust pigment and vehicle applied, and the conventional method of applying three coats using only hydraulic rust removal, or one coat after disk sangu treatment, or A comparison was made between the conventional method and the case of applying 3 coats. This was carried out using a commonly used salt spray test method in order to predict aging deterioration, and it is clear that the method of the present invention is superior in terms of rust prevention effect and cost.

Furthermore, based on this result, approximately 100% of the test AI' was applied to the support of a belt conveyor with a total length of 200m in a coke factory near the coast within a steelworks using the inland water method in Table 1 above.
m, left! 1100m as conventional method) A 8 =
& 9 T-Anti-corrosion construction was carried out, but the cleaning with high pressure water according to the method of the present invention yielded good results as shown in FIG. 1, with good descaling and the paint finish 9 was no different from that of the conventional method.

[Brief explanation of drawings]

Figure i H shows the test results for the 200m+ belt conveyor coating in the coke factory. Koji Shinbe (. □222) Figure 1 Part 1 Q-hand]

Claims (1)

[Claims] Corrosion prevention by spraying high-pressure water containing phosphate or the same effective agent onto structural members to peel off and remove the previously painted film, at the same time forming a chemical conversion film on the surface to be painted, and then adding a rust-inhibiting pigment. A corrosion prevention method for steel structures that involves applying one coat of paint.